Large capacity rechargeable batteries are currently being investigated for use in electric vehicles. The ultimate feasibility of electric vehicles depends on significantly reducing the associated costs. Reduction in the costs of battery assemblies is particularly important in this regard.
Lithium ion batteries are an important type of battery technology. Most battery assemblies, including lithium ion battery assemblies, include a plurality of individual electrochemical cells. Typically, such electrochemical cells include an anode, a cathode, and a separator positioned between the anode and cathode. Typically, the anode includes a metal sheet or foil (usually copper metal) over-coated with a graphitic layer. Similarly, the cathode usually includes a metal sheet or foil (usually aluminum metal) over-coated with a lithium-containing layer. Finally, electrochemical cells include an electrolyte which is interposed between the anode and the cathode. Terminals allow the generated electricity to be used in an external circuit. Electrochemical cells produce electricity via an electrochemical reaction.
For high power application, a plurality of battery cells are utilized and assembled into a battery module. Moreover, such battery modules can include a plurality of metallic (e.g., copper and/or aluminum) cooling fins interspersed between battery cells in a parallel wired battery cell pair. Compression foam pads are typically interspersed between some battery pairs. It turns out that such battery modules typically exhibit temperature differences between the battery cells. Such temperature differences lead to a reduction in battery module performance with a decrease in battery lifetime. Although the prior art cooling fins work reasonably well in cooling the battery cells, improvements are still desirable.
Accordingly, there is a need for improved battery module assemblies and a cooling system to be used therein.